Technical and medical endoscopes are delicate optical instruments that are introduced into technical and human cavities for inspecting the interior of the cavities. Such endoscopes can be rigid endoscopes containing a lens system, flexible endoscopes containing a flexible image guiding bundle or video endoscopes.
Most technical and medical endoscopes are mono endoscopes, though stereo endoscopes have been known in the art since 1904, when Louis & H. Loewenstein received a German patent for a stereo endoscope. Stereo endoscopes are more complex and have a lower brightness than mono endoscope because the cross section available for the optical system of a stereo endoscope is divided between a left image channel and a right image channel. Further, because stereo endoscopes include left optical and right optical channels, those channels must be properly aligned so that the images of the two optical channels overlap within very tight tolerances.
In spite of the complexity and shortcomings of stereo endoscopes, their use has proliferated with the increased demand and execution of minimally invasive surgical procedures, which require handling of surgical instruments under visual control. Mono endoscopes have shown to be poorly configured for such procedures. As a consequence, special endoscopic procedure stereo endoscopes have been developed and in some cases successfully used. The demand for stereo endoscopes has also increased with the advent of robotic surgical procedures and the availability of stereo displays. Because of the rise in use of stereo endoscopes, challenges have arisen in connection with the repair of damaged stereo endoscopes, and particularly, with the inspection, testing and aligning of stereo endoscope optical channels.
More particularly, during assembly of a stereo endoscope optical system, the left optical channel and the right optical channel are evaluated independently to ensure that each optical channel meets certain specified optical parameters and that the quality of the transmitted image for the channel is clear and crisp. Thereafter, the two optical channels are aligned relative to one another. To align the two optical channels, the two optical channels are observed relative to an optimal position. During this alignment, the optical elements that compose the optical trains of the left optical channel and the right optical channel are moved. As a result, the optical parameters and the optical qualities of the two optical channels can change to such a degree that they no longer meet the desired optical parameters. Therefore, it is imperative to control the optical parameters and the optical qualities of the two optical channels, as well as the stereoscopic alignment, of the two channels relative to one another during the alignment process.
Stereo endoscope manufacturers utilize stereo cameras and monitor systems, as part of the stereo endoscopic equipment, to control the optical parameters and the optical qualities of the two optical channels during the alignment and assembly process. Independent service providers who repair stereo endoscopes often do not have access to such stereo cameras and monitor systems. Additionally, hospitals and physicians often do not have access to such equipment when it is desired to inspect and test a stereo endoscope to ensure that the endoscope is proper working condition. This can occur when stereo documentation system of the endoscope manufacturer is not available or the equipment is in use or already sterilized.
Accordingly, there is a need for an optical tool that can be used in conjunction with monoscopic equipment to test and compare the quality of the right and left optical trains that compose a stereo endoscope optical system, as well as the stereoscopic alignment of the two optical systems relative to one another. Such a tool should be simple to use, stably constructed and manufactured at a reasonable cost. Such a tool could be used at several alignment stations in a repair facility, as well as be integrated in a field test kit.